04-11-2020, 10:25 PM
This may not be a good critique since I'm not sure what you ultimately want your art to look like, but I'll tell you my first impressions. I'm not sure if the problem is that the values are "off" so much as there is little contrast between the lit parts and the shadowed parts (except when there is rim light present), which can contribute to a muddy look. In the case of the first image, I wasn't sure if the light source was coming from straight above or not until I looked at his nose shadow. The second image works much better; the planes of the guy's face are better defined and the rim light gives some much-needed contrast. As an experiment, bump up the contrast on one of your images about 70% and see if you like the result.
If you prefer a style with low-contrast values, it would probably help to have more clearly delineated light and shadow planes; not necessarily cel shading, but closer to it. Right now, you've got a painterly style going on with a lot of visible brush strokes, and there's nothing wrong with that, but it can make it harder to figure out what's in light and what's in shadow if there are no strong contrasts. It's also hard to make a painterly style work with thick line art; part of the reason that the second image works better is that you toned down the line-art a lot.
If you prefer a style with low-contrast values, it would probably help to have more clearly delineated light and shadow planes; not necessarily cel shading, but closer to it. Right now, you've got a painterly style going on with a lot of visible brush strokes, and there's nothing wrong with that, but it can make it harder to figure out what's in light and what's in shadow if there are no strong contrasts. It's also hard to make a painterly style work with thick line art; part of the reason that the second image works better is that you toned down the line-art a lot.